Cutaneous Drug Erruptions

Question 1

Types of allergic cutaneous drug eruptions?

Answer 1

Immunologically mediated reactions (allergic)
-Type 1: anaphylactic reaction
Type 2: Cytoxic reactions (pemohigus/pemphigoid)
Type 3: Immune complex mediated reactions (rash)
Type 4: Cell mediated delayed hypersensitivity reactions
-T cell mediated

Question 2

Non- immunological reactions?

Answer 2

• Eczema
• Drug induced alopecia
• Phototoxicity
• Skin erosion due to topical 5-fluorouracil
• Atrophy due to atopical corticosteroids
• Psoriasis
• Pigmentation
• Chellitis/xerosis

Question 3

Presentation of reactions?

Answer 3

Pigmentation 
Itch/pain 
Photosensitivity 
Urticarial 
Exanthematous

Question 4

Who to consider for a drug reaction?

Answer 4

Any patient taking medication who suddenly develops a symmetrical skin eruption

Question 5

Risk factor for drug eruptions?

Answer 5

• Age (young adults)
• Gender (females)
• Genetics
• Concomitant disease (viral)
• Immune status

Question 6

Risk factors for drugs involved in eruptions?

Answer 6

• Chemistry (Blactam.NSAIDS)
• Route (topical v oral/systemic)
• Dose
• half life

Question 7

Most common type of drug eruption?

Answer 7

Exanthematous

Question 8

What type of hypersensitivity is exanthematous drug eruption?

Answer 8

T cell mediated delayed type hypersensitivity (type iv)

Question 9

Description of exanthematous drug eruption?

Answer 9

Mild & self-limiting

• Widespread symmetrically distributed rash
• Mucous membrane spared
• Pruritus
• Mild fever

Question 10

Indicators of a potentially severe exanthematous drug eruption?

Answer 10

• Involvement of mucous membrane & face
• Facial erythema & oedema
• Widespread confluent erythema
• Fever
• Skin pain
• Blisters, purpura, necrosis
• Lymphadenopathy
• SOB, wheezing

Question 11

Drugs associated with exanthematous eruptions?

Answer 11

• Penicillins
• Sulphonamides
• Erythromycin
• Streptomycin
• Allopurinol
• Anti-epileptics
• NSAIDs
• Chloramphenicol

Question 12

What type of hypersensitivity is urticarial drug reactions?

Answer 12

Urticarial
-usually an immediate IgE mediated hypersensitivity reaction (Type 1) after rechallenge with drug (B lactam ABs)
OR
direct release of inflammatory mediators from mast cells on first exposure

Question 13

What might an urticarial reaction be associated with?

Answer 13

Angioedema or anaphylaxis

Question 14

Pustular or bullous drug erruptions?

Answer 14

Acneiform (glucocorticoids)

Acute generalized exanthematous pustulosis (ABs, CCB)

Question 15

What is drug induced bullous pemphigoid caused by

Answer 15

ACE inhibitors
Penicillin
Furosemide

Question 16

What disease can be triggered by vancomycin?

Answer 16

Liner IgA disease

Question 17

Characteristics of a fixed drug eruption?

Answer 17

Well demarcated round/ovoid plaques

• Red painful
• Hands, genitalia, lips, oral mucosa

Question 18

Presentation of fixed drug eruptions?

Answer 18

Eczematous lesions
Papules
Vesicles
Urticaria

Question 19

Drugs associated with fixed drug eruptions?

Answer 19

Tetracycline, doxycycline
Paracetemol
NSAIDs
Carbamazepine

Question 20

Cutaneous & systemic symptoms of severe cutaneous adverse drug reactions?

Answer 20

• Stevens-Johnson Syndrome
• Toxic epidermal necrolysis
• Drug reaction with eosinophilia & systemic symptoms (DRESS)
• Acute generalised exanthematous pustulosis

Question 21

Acute phototoxic drug reactions?

Answer 21

Skin toxicity- photosensitivity
Systemic toxicity
Photodegradation

Question 22

Chronic phototoxic drug reactions?

Answer 22

Pigmentation
Photoageing
Photocarcinogenesis

Question 23

What type of immunity phototoxic cutaneous drug reactions?

Answer 23

Non-immunological skin reaction arising in an individual exposed to enough photo-reactive drug & light of the inappropriate wavelengths

Question 24

Patterns of skin phototoxicity?

Answer 24

• Immediate prickling with delayed erythema & pigmentation
• Exaggerated sunburn
• Exposed telangiectasia
• Delayed 3-5 days erythema & pigmentation
• Increased skin fragility

Question 25

Drugs associated with phototoxicity?

Answer 25

• AB’s (fluoroquinolones, doxycycline)
• Thiazides
• Chloropromazine
• NSAIDs
• Quinine
• Psoralens
• Amiodarone
• Porphyrins
• BRAF inhibitors
• Antifungals
• Immunosuppressants

Question 26

Important questions for a history?

Answer 26

• Detailed description of reaction
• Timing of onset of symptoms in relation to drug administration
• Previous exposure to drug?
• When did the drug start (in relation to symptoms)
• When was the drug stopped?
• Did stopping the drug affect the symptoms?
• Photograph of reaction?
• Why was the drug being taken?
• Underlying illness
• Comprehensive drug history including prescribed/non prescribed & herbal/alternative remedies
• Previous history of drug reaction, allergy or other illnesses

Question 27

Common culprits of skin erruptions?

Answer 27

Doxycycline
Amiodarone
Chloropromazine
Quinine

Question 28

Proton pump inhibitors can induce?

Answer 28

Sub-acute-cutaneous lupus

Question 29

Investigations for drug erruptions?

Answer 29

History &physical
Less clear situations=
- Phototesting for phototoxic drug reactions
-Biopsies
-Patch & photopatch tests
-Skin prick/intradermal tests
* skin testing not indicated for type iii or T cell mediated (type iv) reactions

Question 30

Management of drug eruptions?

Answer 30

• Discontinue drug if possible
• Use an alternative
• Topical corticosteroids
• Antihistamines
• Allergy bracelets are useful
• Drug adverse effects should be reported via yellow card scheme